This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of the BABY HUG Follow-up Study is to provide structured follow-up of sickle cell infants that were enrolled in the BABY HUG Treatment Study, which was a double-blind, randomized placebo-controlled trial using Hydroxyurea as treatment. This group of children will be followed for growth, development and clinical status until December 31, 2011. Data collected will help to determine the long-term toxicities and unexpected risks associated with treating children with Hydroxyurea at an early age.